The article provides an overview of conditioned vowel shifts (Cz přehláska) in Old Czech. The changes consist in the fronting of back vowels of any height, and they distinguish Czech from other Slavic languages

Vowel fronting is a process whereby back vowels become fronted. In Old Czech, the vowel fronting took place between the 12th and the 14th centuries; it is traditionally called přehláska (calque of the Germanic Umlaut)…